Waves as high as 9m have been reported on China's south-east coast
Typhoon Morakot has struck China's south-east coast, destroying hundreds of houses and flooding farmland.
Almost one million people were evacuated ahead of the storm, which crashed ashore in Fujian province with winds of up to 119km/h (74mph).
Flights were cancelled and fishing boats recalled to shore. A small boy died when a building collapsed.
Morakot has already hit Taiwan, killing at least three people and causing some of the worst flooding for 50 years.
In one incident, an entire hotel - empty at the time - was swept away by the waters.
Chinese state media said that the sky turned completely dark in Beibi, Fujian, when Typhoon Morakot made landfall at 1620 local time (0820 GMT).
Trees were uprooted as high winds and heavy rain lashed the coast.
Some 473,000 residents of Zhejiang province were evacuated before the typhoon struck, as well as 480,000 from Fujian, Xinhua news agency said.
In Zhejiang's Wenzhou City a four year-old child was killed when a house collapsed. Dozens of roads were said to be flooded and the city's airport was closed.
Rescuers used dinghies to reach worst-hit areas; in one area only the tops of trees were said to be showing above the floodwater.
The storm is expected to move north and weaken, but strong winds are expected to persist for three days, forecasters say.
Morakot dumped 250cm of rain on Taiwan as it crossed the island on Saturday, washing away bridges and roads.
Taiwan hotel collapses after typhoon
At least three people were known to have died - a woman whose car went into a ditch and two men who drowned.
Thirty-one others were reported missing, Taiwan's Disaster Relief Centre said. Among them were a group reportedly washed away from a make-shift shelter in Kaohsiung in the south.
At least 10,000 people were trapped in three coastal towns, a local official in the southern county of Pingtung said.
In Chihpen, one of Taiwan's most famous hot spring resorts, a hotel collapsed after flood waters undermined its foundations.
Morakot - which means emerald in Thai - has also contributed to heavy rains in the Philippines. At least 10 people were killed in flooding and landslides in the north.
Typhoons are frequent in the region between July and September.